Soovannalarth, B. . “The Revenue Collection of the Revenue Department in the Central Region of Lao People’s Democratic Republic”. Journal of Graduate MCU KhonKaen Campus, vol. 6, no. 4, Dec. 2019, pp. 661-9, https://so02.tci-thaijo.org/index.php/jg-mcukk/article/view/230195.